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ON-VEHICLE SERVICE TSB Revision MULTIPORT FUEL INJECTION (MFI) <3.0L ENGINE> 13B-555 9. Disconnect the vacuum hose (blue stripe) from the fuel pressure regulator and measure fuel pressure with the hose Standard value: 330 − 350 kPa (47 − 50 psi) at curb idle 10.Check to see that fuel pressure at idle does not drop even after the engine has been revved several times. 11.Revving the engine repeatedly, hold the fuel return hose lightly with your fingers to feel that fuel pressure is present in NOTE: If the fuel flow rate is low, there will be no fuel 12.If any of fuel pressure measured in steps 8 to 11 is out of specification, troubleshoot and repair according to the table 13.Stop the engine and observe fuel pressure gauge reading. It is normal if the reading does not drop within two minutes. If it (1) Squeeze the fuel return line closed to confirm leak-down occurs from defective fuel pressure regulator. (2) Squeeze the fuel supply line closed to confirm leak-down occurs from defective fuel pump check valve. (3) If pressure continues to drop with both fuel lines squeezed closed, injector(s) are leaking. 14.Release residual pressure from the fuel pipe line (Refer to SYMPTOM PROBABLE CAUSE REMEDY • Fuel pressure too low • Fuel pressure drops after racing • No fuel pressure in fuel return Clogged fuel filter Replace fuel filter Fuel leaking to return side due to Replace fuel pressure regulator Low fuel pump delivery pressure Replace fuel pump Fuel pressure too high Binding valve in fuel pressure Replace fuel pressure regulator Clogged fuel return hose or pipe Clean or replace hose or pipe Same fuel pressure when vacuum Damaged vacuum hose or Replace vacuum hose or clean Defective fuel pressure regulator Replace fuel pressure regulator SYMPTOM PROBABLE CAUSE REMEDY Fuel pressure drops gradually after Leaky injector Replace injector Leaky fuel regulator valve seat Replace fuel pressure regulator Fuel pressure drops sharply Check valve in fuel pump is held Replace fuel pump AK000119 |